# 7860
With the caveat that all H7 viruses are not created equal - and that with the exception of H7N9 - H7 viruses are generally considered to pose only a low threat to human health, Australian authorities are reporting an outbreak of an H7 virus (N subtype not specified) at a poultry farm in New South Wales.
First the report from the NSW Department of Primary Industries, after which I’ll return with more.
Avian Influenza confirmed at Young egg farm
15 Oct 2013
H7 Avian Influenza has been confirmed in a flock of 400,000 layer hens near Young, NSW Chief Veterinary Officer Ian Roth said today.
"The results were confirmed by the NSW Department of Primary Industries’ (DPI) State Veterinary Diagnostic Laboratories at the Elizabeth Macarthur Agricultural Institute and CSIRO’s Australian Animal Health Laboratory," Mr Roth said.
"The results confirm that this virus is the H7 Avian Influenza strain, NOT the highly pathogenic H5N1 strain that has gained worldwide attention.
"The property has been quarantined and DPI's First Response Team has been activated to oversee the response and work with the property owners and the egg industry.
"The remaining birds on the property will now be culled in-line with national agreements.
"Control restrictions are now in place within a 10km radius of the quarantined egg farm and extensive surveillance and tracing is now underway to ensure the virus does not spread.”
"The NSW Food Authority has confirmed that there are no food safety issues and that poultry and eggs remain safe to eat.
"There is no evidence that eating food from farms that have been affected by avian influenza have ever caused human illness," NSW Food Authority Chief Scientist, Lisa Szabo said.
Mr Roth said Australia has previously had a small number of outbreaks of H7 Avian Influenza viruses which were all quickly and successfully eradicated.
"Late last year, the DPI and Livestock Health and Pest Authority (LHPA) successfully eradicated an outbreak of H7 Avian Influenza at an egg farm near Maitland," Mr Roth said.
People who notice sick or dead birds should contact their local veterinarian or call the Emergency Animal Disease Watch Hotline 1800 675 888.
Although human infection with H7 viruses have been only rarely reported, and (with the exception of H7N9 in China) have caused mostly mild symptoms, H7 viruses over the past decade have been increasingly viewed as having at least some public health implications.
In 2008 we saw a study in PNAS that suggested the H7 virus might just be inching its way towards better adaptation to humans (see Contemporary North American influenza H7 viruses possess human receptor specificity: Implications for virus transmissibility).
You can read more about this in a couple of blogs from 2008, H7's Coming Out Party and H7 Study Available Online At PNAS.
The emergence of a highly pathogenic (in humans) H7N9 in China last spring has increased these concerns, as has the revelation that a new H7N7 strain emerged in Chinese poultry at roughly the same time (see Nature: Genesis Of The H7N9 Virus).
Ten years ago, the largest known H7 outbreak of human cases (at least until H7N9 in China) was recorded in the Netherlands. In that outbreak, the culprit was H7N7 (albeit from a different lineage than the H7N7 virus described in this Nature Journal letter above).
Details on that cluster were reported in the December 2005 issue of the Eurosurveillance Journal (see Human-to-human transmission of avian influenza A/H7N7, The Netherlands, 2003). Roughly 30 million birds residing on more than 1,000 farms were culled to control the outbreak. One person - a veterinarian who visited an infected farm – died a week later of respiratory failure.
The rest of the symptomatic cases were relatively mild.
The Fraser Valley, British Columbia H7N3 outbreak of 2004 resulted in at least two human infections, as reported in this EID Journal report: Sporadic human cases of avian H7 virus infection linked to outbreaks in poultry have also been reported the UK, Mexico, and most recently Italy (see ECDC Update & Assessment: Human Infection By Avian H7N7 In Italy).
Again, cases were generally mild, with conjunctivitis being the most commonly reported symptom.
While most H7 viruses are currently considered primarily a threat to the poultry industry, H7 flu strains - like all influenza viruses - are constantly mutating and evolving. What is mild, or relatively benign today in humans, may not always remain so.
Which is why we take note of outbreaks such as the one reported today in NSW.
For more on the history of H7 viruses, you may wish to revisit A Brief History Of H7 Avian Flu Infections.
